A remarkable review of the effect of lockdowns during COVID-19 pandemic on global PM emissions

COVID-19 was labeled as a global pandemic when it caused a larger number of death cases in the world. Facing the dangerous and serious global pandemic, many countries have issued the nationwide lockdown, resulting in the shutdown in all places of social gatherings, the traffic, and industrial and manufacturing activities, causing negative impacts on the socio-economical activities. However, a noticeable reduction in NO2, CO2, and PM emissions was globally recorded although this reduction was different for each nation. In this paper, an overall picture of global PM pollution was exhibited during the city-to-nation lockdowns in the COVID-19 period. Overall, the obtained results in this current work might provide confidence to the stakeholders associated with the development of policy for air quality control aiming to achieve a significant improvement in air quality when better control strategies for air pollution are strictly executed.